/* 
 * PROJECT: NyARToolkitCS(Extension)
 * --------------------------------------------------------------------------------
 * The NyARToolkitCS is Java edition ARToolKit class library.
 * Copyright (C)2008-2009 Ryo Iizuka
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * For further information please contact.
 *	http://nyatla.jp/nyatoolkit/
 *	<airmail(at)ebony.plala.or.jp> or <nyatla(at)nyatla.jp>
 * 
 */
using System.Diagnostics;
namespace jp.nyatla.nyartoolkit.cs.core
{



    /**
     * このクラスは、明点・暗点のPTail法で求めた敷居値を合算して、敷居値を計算します。
     * <p>敷居値決定のアルゴリズム - 明点・暗点両側からPTail法を用いて一定割合の画素を取り除き、その中間値を求めます。</p>
     */
    public class NyARHistogramAnalyzer_SlidePTile : INyARHistogramAnalyzer_Threshold
    {
        private int _persentage;
        /**
         * コンストラクタです。
         * @param i_persentage
         * 明点、暗点の両側から取り除く、画素の割合を指定します。0&lt;n&lt;50の範囲で指定します。
         */
        public NyARHistogramAnalyzer_SlidePTile(int i_persentage)
        {
            Debug.Assert(0 <= i_persentage && i_persentage <= 50);
            //初期化
            this._persentage = i_persentage;
        }
        /**
         * この関数は、SlidePTileを用いて敷居値を1個求めます。敷居値の範囲は、i_histogram引数の範囲と同じです。
         */
        public int getThreshold(NyARHistogram i_histogram)
        {
            //総ピクセル数を計算
            int n = i_histogram.length;
            int sum_of_pixel = i_histogram.total_of_data;
            int[] hist = i_histogram.data;
            // 閾値ピクセル数確定
            int th_pixcels = sum_of_pixel * this._persentage / 100;
            int th_wk;
            int th_w, th_b;

            // 黒点基準
            th_wk = th_pixcels;
            for (th_b = 0; th_b < n - 2; th_b++)
            {
                th_wk -= hist[th_b];
                if (th_wk <= 0)
                {
                    break;
                }
            }
            // 白点基準
            th_wk = th_pixcels;
            for (th_w = n - 1; th_w > 1; th_w--)
            {
                th_wk -= hist[th_w];
                if (th_wk <= 0)
                {
                    break;
                }
            }
            // 閾値の保存
            return (th_w + th_b) / 2;
        }
    }
}